Embodiments of the invention relate to the field of electric field sensing, and more particularly to resonant tunneling based electric field sensors.
Stand-off sensing of an electric field may be required in certain applications. For example, non-invasive sensing may be required so that the electric field is not disturbed by the presence of an external body (sensing device). In one example application, the electric field to be sensed may be in a range from about 10 microvolt per meter to about 100 microvolts per meter at a stand-off distance of about 1 cm. Application specific frequency ranges may be in a range from about 0.5 Hz to about 30 Hz with bandwidth bins of about 5 Hz.
Conventional approaches to stand-off electric field sensing include optical approaches, capacitive approaches and approaches employing a superconducting quantum interference device (SQUID). SQUID requires cryo-cooling, hence, is not considered viable from a monetary and space point of view. Optical approaches for stand-off electric field sensing rely on electro-optic effects. Optical devices for such optical approaches can meet sensitivity requirements, however, these optical devices face challenges with regard to packaging requirements from a size, weight and cost perspective. Capacitive approaches provide a global optimum with respect to stand-off distance, however, disadvantageously, the capacitive devices, such as capacitive sensors suffer from low frequency electronic noise.
Accordingly, there is a need for electric field sensing devices that have reasonable sensitivity and are easy to package.